There are some houses with in-laws; of course finding one for rent is few and far between. One of (maybe the) nation's largest home builder, Lennar, they don't build in MA, but in 26 other states, and one of their most popular models is an in-law, with a separate kitchen, garage, everything; My parents live next to one, it's perfect for in-laws. Just mentioning it in case your move ends up being out of state, that's an easy way to find what you are looking for.